class Tools{
    //随机字符串
    static randomString(len) {
        len = len || 32;
        var $chars = "ABCDEFGHJKMNPQRSTWXYZabcdefhijkmnprstwxyz2345678";
        var maxPos = $chars.length;
        var pwd = "";

        for (var i = 0; i < len; i++) {
            pwd += $chars.charAt(Math.floor(Math.random() * maxPos));
        }
        return pwd;
    };
}